Enhanced activity of Co catalysts supported on tungsten carbide-activated carbon for CO2 reforming of CH4 to produce syngas

Abstract

Carbon materials are widely used as catalysts or supports due to their excellent properties. In this paper, the tungsten carbide-activated carbon (WC-AC) composite support was successfully prepared by in-situ carburizing on AC matrix, which is characterized by the covalent anchoring of WC on the AC support. The active metal Co was supported on WC-AC for dry reforming of methane (DRM). Samples were analyzed by N2 physisorption measurements, XRD, XPS, H2-TPR, H2-TPD, CH4&CO2-TPSR, TG-DTG. The WC-AC stabilizes the disturbance of C in AC, alleviates the gasification effect of CO2 and increases the active sites for CH4 cracking. Moreover, WC provides a resistance-less bridge suitable for the Co3+ → Co2+, resulting in a high Co2+/Co3+ ratio on the catalyst surface. This enhances the interaction between the Co species and the WC-AC, thereby enhancing the CH4 activation. In the process of WC-AC promoting Co3+→Co2+, the catalyst surface is accompanied by the generation of oxygen vacancies. This can enhance the dissociative adsorption of CO2 on surface of the WC-cobalt oxide, and at the same time increase the relative proportion of adsorbed oxygen on the catalyst surface, thereby effectively inhibiting the formation of coke. However, the small amount of graphitic carbon generated due to the strong coupling of WC and Co is the main reason for deactivation of Co/WC-AC.